Machine for training student pilots in handling airplanes



Oct. 1, 1940. FOX 2,216,489

MACHINE FOR TRAINING STUDENT F ILOTS IN HANDLING AIBPLANES Filed May l 7, 1938 4 Sheets-Sheet 1 Trader/'0 4 I, F0 .22,

Q w W mcamE FOR TRAINING STUDENT PILOTS m HANDLING AIRILANES F. L. FOX

Oct. 1. 1940.

Filed May 17, 1938 4 Sheets-Sheet 2 F. L. Fox

Oct; 1, 1940.

HACHINE FOR TRAINING STUDENT PILOTS IN HANDLING AIBPLANES Filed May 17, 1958 4 Shoots-Sheet 3 grwo/wk b frederickl. Fox

F. L. FOX

Get. 1, 1940.

MACHINE FOR TRAINING STUDENT PILOTS IN HANDLING AIRPLANES Filed'ua 17, 1958 4 sheets-sheet 4 Trader/ckf'bx,

Patented Oct. 1, 1940 UNITED STAT S 2.21am memo s'ronnn'r rmo'rs MACHINE FOR PATENT orrlcs 11 Claims.

This invention relates to machines for training student pilots in handling airplanes, and the primary object of the present invention is to provide features capable of embodiment in a 5 training machine adapted to solely travel upon the ground for use as a primary training machine, or capable of embodiment in a machine adapted for flight to afford advanced training.

Another object of the present invention is to a provide a training machine of the above kind having two independent sets of movable controlling planes, one set being adapted to be operated for the purpose of creating unfavorable conditions such as may be met with in actual ll flight, and the other set being under the control of the student pilot so that he may receive training in overcoming these unfavorable conditions. It is contemplated to provide means for operating the first-mentioned set of controlling planes m either mechanically or manually. When manual operating means is provided for the firstmentioned set 'of controlling planes, the latter are preferablyof such a character as to enable the instructor pilot in chargethereof to take control of the machine away from the student pilot in an emergency. For this purpose, the present invention further contemplates providing the said first-mentioned set of controlling planes so that they have greater controlling a power than the second-mentioned set of controlling planes. On the other hand, in the ground-type of machine, wherein one set of controlling planes is mechanically operated; that set is preferably of the form or arrangement a to have a lesser controlling power than the set controlled by the student pilot, so that the student pilot may have actual control over the machine as is necessary in the absenceof an instructor pilot.

w The present invention is essentially identified with machines capable of free travel, as opposed. to machines of the captive 'type having restraining means restricting direction of travel, etc. Accordingly; a training machine embodying the present invention isin the general form and construction of an airplane having propelling means and capable of free'movement on the ground or in the air, depending upon whether the machine is adapted for primary ground w training or advance free flight training.

A still further ob'iect of the present invention is to provide, inpthe type oi training machine adapted for free flight, means for giving the student control overpany. one or more of the sets of secondarrcontrollins p anes. a d to pro-.

bodying the present invention.

vide means, operable by the instructor pilot, for

quickly rendering such controls inoperable by the student pilot in case of an. emergency. An advantage of this provision is that advance training may be given in stages or degrees as thestudent pilot improves in his ability to handle the machine, at the same time making it possible" for the instructor pilot to take charge of the machine in an emergency and avoid a disaster; v

With the above. general objects and features in view, and others that will become apparent as the nature of the invention is better understood, the present inventlon consists in the novel form, combination and arrangement of parts hereinafter more fully described, shown in the accompanying drawings and claimed.

In the drawings:

Figure 1 is a top plan view, somewhat diagrammatic, of a machine embodying the present invention adapted for free travel upon the ground and for use as a primary ground training ma chine.

Figure 2 is a side elevational view of the machine shown in Figure 1.

Figure 3 is a front elevational view thereof.

Figure 4 is an enlarged fragmentary longitudinal section on line 4-4 of Figure 1.

Figure 5 is a fragmentary transverse section taken on line 5-5 of Figure 4.

. 80 Figure 6 is a diagrammatic perspective view showing the arrangement of the sets of'movable controlling planes employed in the machine of Figure 1, together with the operating means therefor.

Figure '7 is a view .similar to Figure 2 of a a machine of the type adapted for free flight, em-

Flgure 8 is a top plan view of the machine shown in Figure 7.

Figure 9 is a view similar to Figure 6 of the controlling planes and operating means therefor forming part of the machine shown in Figure '7.

K Figure 10 is a fragmentary top plan view illustrating a modified arrangement of the sets of movable controlling planes.

Figure .ll i's a fragmentary perspective view showing a still further modificationbf the arrangement oi movable controlling planes.

Figure 12 is a view similar to Figure 9 illustrating-a modification of the free flight machine of Figure 7 with respect to the means for operating the two sets of movable controlling planes, whereby the studentpilot may be given control of any desired one or more of the sets of primary controlling planes, and whereby the instructor pilot may render such controlling planes inoperable by the student pilot, at will.

Figure 13 is a fragmentary view partly in side elevation and partly in longitudinal section, illustrating details of the operating means forming part of the modification shown in Figure 12.

Figure 14 is an enlarged horizontal section on line I4-I4 of Figure 13.

Figure 15 is a fragmentary verticalsection on line I5I5 of Figure 13.

Figure 16 is an enlarged perspective view of the lever forming part of the means for enabling the instructor pilot to render the primary elevator planes inoperable by the student pilot.

Figure 17 is an enlarged perspective view of the lever forming part of the means for enabling the instructor pilot to render the primary set of ailerons inoperable by the student pilot.

Figure 18 is a view similar to Figure 16 of the lever forming part of the means shown in Figure 14 for enabling the instructor pilot to render the primary vertical rudder inoperable by the student pilot; and

Figure 19 is an enlarged fragmentary section on line I9I9 ofiFigure 13.

Referring to the drawings, the embodiment or form of the invention shown in Figures 1 to 6 inclusive is in the general form and construction of an airplane of the monoplane type, although not adapted for flight and only being intended for and capable of free travel upon the ground. This embodiment includes a body or fuselage 5 having laterally extending wing-like supports 6 which are not intended or constructed to act as sustaining planes for free flight but merely act as supports for ailerons as will be presently described.

In the center line of the body or fuselage 5, approximately at the center of gravity, a' single downwardly opening pocket .I is formed, and in "this pocket there is mounted a single supporting and driving wheel 8. This wheel is preferably provided with a pneumatic tire and is non-retractable, and is shown as being driven by a suitable engine or motor 9 mounted within the forward portion of the body or fuselage 5 and operatively connected with the wheel 8 by suitable chain or other gearing I0.

The machine is provided with the usual movable con-trolling planes including ailerons II carried by the wing-like supports 6, elevators or horizontal rudders I2 carried by the tail end of the body or fuselage 5, and a vertical rudder I3 for lateral steering is also carried by the tail end of the body or fuselage 5 intermediate the elevators I2. This set of ordinary movable controlling planes is provided'with the usual well known or any preferred form of manual operating means, the operating means illustrated including the usual lever or joy stick I4 for manipulating the ailerons II and elevators I2, and an ordinary foot lever I5 for actuating the vertical steering rudder I3. The connections between the hand lever I4 and foot lever I5 and the respective steering and controlling planes II, I2 and I3 include suitable cables as illustrated clearly in Figure 6, and are of ordinary or well knowntype. The control levers I4 and I5 are arranged as usual within the the body or fuselage 5 in front of a seat I5 adapted to be occupied by the student pilot so that he may conveniently manipulate the steering and controlling planes II, I2 and I3. The wheel I! serves not only as a running support for the machine but also as a pivotal support on which it may tilt laterally or vertically, 1. e., in a fore and aft direction. It will thus be seen that substantially the same degree of skill is required to balance the ground training machine while traveling on the single supporting wheel at a predetermined speed over'the ground. as is required to balance an airplane laterally and longitudinally while in free flight.

In order to create unfavorable conditions such as are met with or encountered during actual flight, I provide a secondary set of controlling planes including auxiliary ailerons I la, and auxiliary horizontal rudders or elevators I2a, adapted to be operated for the purpose of creating conditions which must be overcome bythe student pilot through operation of the control levers I4 and I5 and consequent actuation of the primary steering and controlling planes II, I2 and I3. In order to give the student absolute control of the machine at all times, the controlling planes II and I2 have a controlling power which predominates that of the secondary or auxiliary controlling planes IIa and I2a. This may be accomplished by giving the primary controlling planes II and I2 greater degree of movement, greater area, and/or greater controlling leverage than that of the auxiliary controlling planes Ha and Ho, the greater area being provided by simply making the controlling planes II and I2 of greater size or area than that of the auxiliary planes Ila and I20, and/or the greater controlling leverage being simply provided by placing the primary controlling planes II a greater distance from the longitudinal center of the fuselage 5 than the planes Ila, and extending the planes I2 laterally from such longitudinal center a greater distance, as shown. In the construction of Figure 1, the secondary controlling planes Ila are made of smaller size or lesser area than the primary controlling planes II, and are arranged on the rear edge of the support 6 inwardly of the primary controlling planes I I nearer the longitudinal axis of thefuselage. Thus, the primary controlling planes II are of greater controlling leverage and area than the secondary controlling planes IIa. Substantially the same condition maintains with respect to the secondary controlling planes I2a as compared with the corresponding primary controlling planes or elevators l2. The latter, however, may be conveniently placed rearwardly of the secondary elevators I2a as shown clearly in Figures 1 and 6, and while both greater leverage and pressure area may be utilized, either way may be used alone for'enabling the primary controlling planes 'II and I2 to have a controlling effect which predominates over the controlling eifect of the secondary controlling planes IIa and I2a. In the case of biplanes, the primary ailerons I I' may be provided on the upper supporting planes or wings 6a, and the secondary ailerons II may be provided on the lower supporting planes or wings 6b, as shown in Figure 11. Predominatlng controlling influence is provided for the primary ailerons II' in this arrangement by simply making the latter of greater area. As shown in Figure 10, the primary ailerons Il may be provided on the supporting plane or wing 80 of a monoplane and provided with a cut-out I 8 within which the secondary aileron II is arranged, the primary alleron II being of greater size and leverage.

While the secondary controlling planes Ma and I2a may be manipulated by an instructor pilot seated in the machine in front of the student pilot, I have shown the secondary controlling planes Ila and I2a as provided with I,"

side cam groove I9 engaged by one end of a rod 20 operatively connected with the secondary elevators I2o. further has a peripheral cam groove 2I engaged by an end of a rod 22 operatively connected with the secondary ailerons Ila, andby driving the rotatable member II, the secondary conable conditions and thereby familiarizing himself with the control of the machine. This is of course carriedout while the machine is in motion or being driven about upon the ground through the medium of the driving and supporting wheel 8 driven by the engine 9. In this way, the student pilot may be given primary training in thehandling of airplanes with comparative safety and no danger of disastrous crashes such as often occur when primary training is attempted'in actual flight; As the machine is capable of free movement along the ground unrestricted by any towing or guiding means, the student must of course have full control at'all times of lateral steering through operation of the vertical rudder I3, and no secondary vertical steering rudder is provided to be opposed by the student pilot. In actual practice, any suitable or well known means may be provided for unclutching the driving and supporting wheel 8 from the engine 9, and it is also desired to have a clutch 23 in the driving connection between the motor 9 and-the rotatable cam member I1. Thus, the secondary controlling planes Ila and I2a may beleft stationary in the very first lessons which are given to thestudent pilot, so that he can initially sim-- ply get the feel of the steering and controlling means. As the student progresses, the mechanical means for actuating the secondary controlling planes may be utilized to set up the unfavorable conditions mentioned which are to be opposed by the student pilot through actuation of the primary controlling planes. Also, the clutch 23 may have suitable actuating means within convenient reach of the student pilot occupying the seat I6 so as to throw this mechanical actuating means out of operation at will. Naturally, a very desirable amusement device would be afiorded by a machine constructed as illustrated in Figures 1 to 6 inclusive, with the secondary controlling plane and the mechanical actuating means therefor omitted.

It is desirable to provide anti-friction means on the outer end of the supports 6 or the outer primary ailerons II, capable of engaging the ground if the machine should tilt laterally to an undue degree, so that the forward travel of the machine will not be interfered with and whereby proper support for the machine is provided in a laterally tilted position when the machine is not in motion. Such anti-friction means may consist of small wheels 24 journaled on the undersides of the primary ailerons II, with the lower portions thereof considerably abovethe tread plane of the central driving and support- The rotatable member II ing wheel 8, as well as slightly rearwardly of the latter. As will be seen from Figure 3, the lateral angle between the horizontal and lines drawn from the tread point of the wheel 8 to the wheels 24, is of a predetermined degree so as to enable the same to operate at the best advantage in acting as balancers or lateral tilt limiting means. In other words, the wheels 24 are supported with their ground-engaging portions abovethe tread plane of thewheel 8 to form lateral base angles for banking when turning as the machine travels along the ground. By providing the wheels 24 on the movable ailerons II, the latter may be manipulated so as to forcibly raise that support 6 which has been lowered through lateral tilting of the machine, thereby bringing the machine quickly back to a state of lateral equilibrium.

The embodiment or form of the invention shown in Figures 7 to 9 inclusive is in the gen eral form and construction of an airplane of the monoplane type adapted for actual free flight for use in giving advanced or free flight training. This embodiment includes a body or fuselage 5a having laterally extending wings 8d constructed to act as sustaining planes, and ,provided with suitable landing gear and tail skid or wheel 26 common to conventional airplaneconstruction. The machine also has the usual motor-operated propeller 21 and complete standard steering and .controlling equipment including primary ailerons II primary elevators or horizontal rudders I2 and primary vertical steering rudder I 3. The primary steeringand controlling planes II I2 and I 3 have conventional manual operating means, such as the ordinary lever or joy stick I4" for actuating the ailerons I I 5 and elevators I2, and the foot lever I5 for operating the primary steering rudder I3. This machine isof the two-seater type, with the control levers I 4 and I5 arranged within the fuse- -lage 5a in front of the rear seat I8a. A second said secondary steering and controlling planes.

H I2 and I?) being provided with suitable manual operating'means such as a conventional lever or joy stick I4 for manipulating the ailerons II and elevators I2 and an ordinary foot lever I5 for actuating the auxiliary vertical steering rudder I3 In this type of machine, the instructor pilot may create any desired unfavorable conditions such as might be met with or encountered during actual flight, by manipulating the levers I4 and I5 and actuating the controlling planes operated thereby, the student following the motions thus produced and watch-- ing their eflects or operating the auxiliary or secondary controlling and steering planes under guidance from the instructor through the medium of levers I4 and I5 so as to receive training in overcoming these unfavorable conditions. As in the embodiment of Figure 1, the primary controlling and steering planes H l2 and I3 have controlling influence or power predominating that of the secondary controlling and steering planes II, It and I3. In this type of machine, the instructor pilot is placed. in charge of the primary controlling and steering planes having the predominating controlling power or influence, in order that such instructor pilot may thereby avoid any crash or like disaster.

In the type of machine adapted for actual free flight, such as above described and illustrated in Figures '1 to 9 inclusive, it is desirable to give the advanced training to the student pilot in stages, so that he will not be required to learn to master all of the different controlling planes at one and the same time. For instance, the student pilot may initially be given control of only the auxiliary or secondary ailerons 11, only the secondary elevators 12*, or only the secondary vertical rudder I3 and, as the student progresses, he may be placed in charge of two of these controlling planes and then all of them. In order to provide for this training in stages, the type of machine shown in Figures '1 to 9 inclusive may be modified as illustrated in Figures 12 to 18 inclusive. As shown in the latter figures, the lever or joy stick 14 may be mounted on a shaft 28 having an arm 28 rotatably fitted thereon and operatively connected t' the auxiliary or secondary ailerons i I. Also, the lever or joy stick I4 may be connected as at 38 with an arm 3| rotatably fitted on a shaft 32 carrying levers 33 operatively connected to the secondary or auxiliary elevators I2 and the foot lever 15 may be carried by a shaft 34 on which is rotatably fitted a lever 35 connected to the secondary or auxiliary vertical steering rudder I3 Means are provided for releasably keying the arms 29 and 3| and the lever 35 to their respective shafts 28, 32 and 34 and respectively including levers 36, 31 and 38 shown in Figures 12 and 13 and respectively detailed in Figures 1'1, 16 and 18. Each of these levers is pivoted intermediate its ends and is provided at the outer end of one of its arms with an arcuate portion provided with an elongated slot. The arcuate portions of the levers-31 and 38 are respectively indicated at 38 and 48 and their longitudinal elongated slots at 4| and 42, while the arcuate portion of lever 36 is indicated at 43 and its elongated slot at 44, the arcuate portion 43 and its slot 44 of lever 36 being transverse of said lever instead of longitudinally of the latter as with the levers 31 and 38. Slidably carried by the arcuate portion of each of these levers in the longitudinal slot of said arcuate portion is a pin adapted to act as the releasable keying element, the pin of lever 36 being indicated at 36a, the pin of lever 31 being indicated at 31a, and the pin of lever. 38 being indicated at 38a. The pin 36a enters an opening in arm 28 and is adapted to be entered into a socket of shaft 28 so as to key the arm 28 to shaft 28, and the same arrangement is illustrated with respect to'pins 31a and 38a of levers 31 and 38 in Figures 15 and 14, respectively; As shown, the pin 31a is engaged in an opening of the hub of arm 3| and adapted to enter a socket or recess 45 of shaft 32 and pin 38a is engaged in an opening of the hub of lever 36 and adapted to enter a socket 46 in the shaft 34. Obviously, the levers 36, 31 and 38 may be operated to engage the pins 36 31a and 38a in the sockets of their respective shafts 28, 32 and 34, or to disengage them from said sockets to thereby render the levers l4 and Li operative or inoperative for actuating the controlling planes I2 and 13*. The levers 36, 31 and 38 are connected by linkage 41 with an operating lever 48 arranged adjacent the instructor pilot's seat 16a, and any desired one or more of the levers 36, 31 and 38 may be connected to or disconnected from the linkage 41 by means of elevators I2 take control of the machine in an emergency and removable pins 43 pivotally connecting said levers with the linkage 41. As shown in Figure 19, these pins are readily insertable or removable and may be of any preferred or well known construction, the type shown in Figure 19 with respect to the lever 31 being of the spring cotter pin type. In this way, any desired one or more of the pins 48 may be removed before flight is undertaken, thereby arranging in advance for placing the student pilot only in control of those particular controlling planes which it is desired to give him control of. For instance, the lever 31 may be disconnected from the linkage 41, whereupon said lever 31 will swing by gravity to disengage pin 31a from the shaft 32, thereby rendering the students lever or joy stick l4 inoperative for actuating the secondary elevators 12 With the levers 36 and 38 connected with the linkage 41, the student pilot will only have control over the secondary vertical rudder l3 and the secondary ailerons II. In a like manner, the lever 36 may be disconnected from linkage 41 to render the lever l4 inoperative for controlling the ailerons I 1 and/or the lever 38 may be disconnected from linkage 41 to render the foot lever 15 inoperative for controlling the secondary steering rudder 13*. As the lever 38 is horizontally arranged, a tension spring 58 may be utilized for swinging the lever 38 to disengage its pin 38a from shaft 34 when lever 38 is disconnected from the linkage 41, as shown in Figure 14. It will be away from the student pilot in an emergency.

For instance, we mayassume that the lever 31 is the only one left operatively connected by its pin 43 with the linkage 41, in which case the student will only have control over the secondary This lever 31 will, in that event, be connected to lever 48 so that the latter may be actuated by the instructor pilot for movin lever 31 and disengaging its pin 31a from shaft 32 so as to render the arm 3| inoperative for actuation of lever 33 and the elevators l2 connected therewith, by means of the lever or joy stick l4 held by the student pilot. It is thus apparent that advance training may be given to the student pilot with an arrangement of this kind, in stages or degrees, the number of kinds of controlling planes operable by the student pilot being increased as the student pilot progresses in ability to handle the controls. It will also be apparent that this arrangement enables the instructor pilot to take complete control of the machine whenever necessary. Otherwise, ,the construction of Figures 12 to 19 inclusive is the same as that of Figures 7 to 9 inclusive, and

.remaining parts common to both forms are indi- From the foregoing description the construction, mode of use and advantages of my improved training machine will be readily understood and single ground-engaging supporting wheel arranged approximately at the center of gravity of the machine,-power means for driving said sup porting wheel, a primary set of manually operable controlling planes, a secondary set of controlling planes operable independently of the first-named set, and means for operating said secondary set of controlling planes, said primary set of controlcontrolling power predominating that of said secondary set, and power-operated means for actuating said secondary set of controlling planes to create predetermined diflerent adverse flight conditions adapted to be overcon's by operation of said primary set of controlling planes.

3. A machine capable of free flight for advanced training of student pilots in handling airplanes, said machine having a primary set of different kinds of controlling planes manually operable only by an instructor, a secondary set of different kinds of manually operable controllingplanes operable only by a student and independently of the first-named set, and means to individually disconnect any one kind of the controlling planes in the secondary set from the manual operating means thereof, said primary set of controlling planes having controlling power predominating that of said secondary set.

4. A machine capable of free flight for advanced training of student pilots in handling airplanes, said machine having a primary set of different kinds of controlling planes manually operable only by an instructor, a secondary set of difierent kinds of manually operable controlling planes operable only by a student and independently of the first-named set, means to individually disconnect any one kind of the planes in the secondary set from the manual operating means thereof, said primary set of controlling planes having controlling power predominating that of said secondary set, and means manually operable only by the instructor or operator of the primary set of controlling planes for disconnecting the kind or kinds of planes of the secondary set which have been left connected to their operating means.

-5. A machine capable of treeflight for advanced training of student pilots in handling airplanes, said machine having a primary set of different kinds of controlling planes manually operable only by an instructor, a secondary set or diiiferent kinds of manually operable controlling planes operable only by a student and lndepend ently oi the first-named set, means to individually disconnect any one kind of the planes in the sec-'- ondary set from 'the manual operating means thereof, and means manually operable only by the instructor or operator of the primary set of controlling planes for disconnecting the kind or kinds 101 planes of the secondary set which have been left connected to their operating means.

6. A machine for primary ground training oi.

. student pilots in handling airplanes, comprising a fuselage having a single ground-eng ging supporting wheel arranged approximately at the center of gravity of the machine, power driven propelling means for the machine, wing-like supports extending laterally from the fuselage, a primary set of manually operable, ailerons carried by said wing-like supports, a secondary set of ailerons operable independently. of the first-named set and carried by said wing-like supports, means for operating said secondary set of ailerons, said primary set of ailerons havin'g controlling power predominating that of said secondary set, and wheels iournaled on the primary ailerons at the trailing edges of the latter and engageable with the ground upon lateral tilting oi the machine.

7. A power-propelled machine capable of free travel on the ground for training student pilots in handling airplanes, said -machine including wheeled supporting means permitting free longitudinal and lateral tilting of the machine, a primary set of manually'operable controlling planes, a secondary set of controlling planes operable independently of the first-named set, said primary set oi controlling planes having controlling power predominating that of said secondary set, means for actuating said secondary set of controlling planes to create a plurality of predetermined different adverse flight conditions to be overcome by operation of said primary set of manually operable controlling planes, a motor for driving said last-named means, and means for rendering said last-named means operative or inoperative at will.

8. A power propelled machine capable of free travel for training student pilots in handling airplanes, said machine including a set of manually operable controlling planes, a second set of controlling planes operable independently of the first-named set, means for actuating said second set of controlling planes to create a pluralityoi. predetermined different adverse flight conditions to be overcome by operation of said first-named set of manually operable controlling planes, a

driving motor for said last-named means, and means to render said last-named means operative .or inoperative at will.

9. A machine capable of free flight for advanced training of student pilots in handling airplanes, said machine having a primary set of diflerent kinds of controlling planes manually operable only by an instructor, at secondary set of different kinds of manually operable'controlling planes operable only by a student and independently oi theflrst-named set, an actuating member for each kind of plane in the secondary set, a manually operable operating member for each actuating member, a latching device for connecting each actuating member with its operating member, means to render any desired one of said latching devices inoperative with the associated actuating member disconnected from its operating member, and meansi manually operable only by the instructor for rendering inoperative any of the latching devices which have been left operative.

10. A machine capable of free flight for advanced training of student pilots in handling airplanes, said machine having a. primary set of difi'erent kinds of controlling planes manually operable only by an instructor, at secondary set of different kinds of manually operable controlling planes operable only by a student and independently of the first-named set, an actuating member for each kind of plane in the secondary set, a manually operable operating member for each actuating member, a latching device for connecting each actuating member with its operating member, means to render any desired one of said latching devices inoperative with the associated actuating member disconnected from its operating member, each latching device including a lever, an actuating rod for the levers of said latching devices, and an operating lever for said rod operable only by the instructor for rendering and carried by said wing-like supports, means for operating said secondary set 01 ailerons, said primary set of ailerons having controlling power predominating that of said secondary set, and supporting elements carried by the primary ailerons at the trailing edges of the latter and engageable with the surface upon lateral tilting of the machine.

FREDERICK L. FOX. 

